primary source造句怎么写

The wheel web, by virtue of its geometry and material characteristics, is a good emitter of high-frequency sound, and is believed to be the primary source of curve squeal noise.

Between budget cutbacks, layoffs and reductions in benefits or increases in hours, clearly our paychecks are not our primary source of satisfaction.

Many parasitic, tropical, and "orphan" diseases are infrequent in the developed world, the primary source of revenue for medicines manufacturers.

Academic journals tend to be the primary source of news for science reporters because that is where researchers usually publish their findings.